Cutting processes have always been an integral part of the manufacturing industry, what many do not know is that there are varying methods of cutting metal, Each process has different capabilities, limitations, and costs associated. While some Methods have been around as early as the mid-1800s, others are relatively new. In this post, we will break down the five processes that give the manufacturing industry the ability to cut through metals.
# 1 Chip Forming
Chip Forming is a metal cutting process that uses mechanical means like sawing, milling, drilling, and turning. This method was pioneered by Kivima and Franz in the 1950s. This metal cutting process is often described in regards to a three-way model, this model is widely known in the machine tool design industry. During these methods, the material is gradually removed from the workpiece in smaller “chips.” Under the umbrella of chip forming are varying operations that utilize the process to remove excess material, below is a brief overview of just a few.
- Milling: an operation where rotary cutters remove material.
- Advantages: multi-axes capabilities and can be done on various scale projects.
- Disadvantages: high price point and requires highly skilled operator
- Drilling: an operation where a drill bit removes material by rotating at fast speeds.
- Advantages: sharp edges on the entry side
- Disadvantages: creates burrs and can alter the mechanical properties of the material through stress.
- Turning: an operation that uses a non-rotary tool bit while the workpiece rotates to “chip” away at excess material.
- Advantages: Can be done manually or automatically and easy collection of chips
- Disadvantages: deflects often occur which affect dimensions and roughness.
#2 Shearing
Shearing is a process that is often referred to as die cutting and originated in the mid-1800s when looking for a way to cut leather for the shoe industry. Now the process is used for a variety of different materials and is a way metal can be cut without chipping or the use of heat. This process uses a moving blade to push against the fixed workpiece. Within the process of shearing, there are various operations. Below we have highlighted the most popular two.
- Punching: an operation that uses a punch press to force a tool through the raw material to create a hole and shave away excess material.
- Advantages: cost-effective process for simple cuts and quick operation
- Disadvantages: not optimal for complex cuts and tooling charges can increase quickly.
- Stamping: an operation that cuts metal by using a machine to deform the unwanted material and create varying shapes.
- Advantages: high level of automation and reduces some secondary costs.
- Disadvantages: custom stamping dies bring about a high price point and alterations can not be made during production.
#3 Abrasive Material Removal
Abrasive cutting methods include operations such as grinding, lapping, and waterjet cutting. These cutting methods all remove excess material through erosion. These operations are much faster than heat processes like EDM & laser, offer better edge quality, and typically provide some sort of cost savings for manufacturers. Abrasive material removal is categorized by various operations which are broken down below.
- Grinding: In grinding operations, a grinding wheel is used as the primary cutting tool. Within grinding there are even more specific and individualized operations such as creep-feed grinding, cyclical grinding, and surface grinding.
- Advantages: highly accurate dimensions, can create smooth surfaces, and can be done with lesser pressure applied on the material.
- Disadvantages: does not allow for large amounts of material to be removed.
- Lapping: In lapping, two surfaces are rubbed together with an abrasive material lying between them. This movement can be done by hand or by using a machine.
- Advantages: can hold tight tolerances and great for creating uniformly flat surfaces.
- Disadvantages: slow-cutting processes and expenses can quickly add up resulting in a higher price point.
- Waterjet Cutting: In waterjet cutting operations a large machine uses a mixture of highly pressurized water and an abrasive garnet to cut through varying materials.
- Advantages: cold cutting processes, no thermal damage/distortion, exceptional edge quality, no required finishing processes, a vast array of compatible material types & thicknesses, and extremely tight tolerances can be held.
- Disadvantages: moderate price point
#4 Heat
Metal cutting by heat includes operations such as plasma cutting and laser cutting. Both of these processes use hot, high-powered light to cut away excess material. Laser cutting which originated in the 1960s and plasma cutting which was introduced in 1957 have long been some of the most well-known methods of metal cutting. Despite both of these operations being widely accepted methods of cutting, they do create thermal damage, significant distortion, and require some finishing processes. Laser and Plasma cutting operations are characterized below.
- Laser Cutting: This technology which uses a laser to vaporize and carve away excess materials. While laser used to primarily be used in manufacturing it is now utilized in various industries.
- Advantages: can handle complex cuts and has high accuracy.
- Disadvantages: material type restrictions, material thickness restrictions, required edge clean-up, and high heat inputs.
- Plasma Cutting: An operation similar to laser cutting, but instead uses a jet of accelerated hot plasma to cut through the electrically conductive materials.
- Advantages: low price point, fast cutting speeds, and ease of use.
- Disadvantages: material type restrictions, material thickness restrictions, required edge clean-up, and high heat inputs.
#5 Electrochemical
Electrochemical cutting methods include processes such as electrical discharge machining (EDM), etching, and electrochemical machining (ECM). These operations perform a cut through an electrical and chemical reaction.
- EDM: a fabrication process where the cuts are created by an electrical charge (spark). It is for this reason that EDM is sometimes referred to as spark machining, spark eroding, or wire burning.
- Advantages: can hold tight tolerances, great for creating uniformly flat surfaces.
- Disadvantages: high heat input, some thermal damage, and edge cleanup/finishing processes are often needed.
With so many processes and operations available today manufacturers have a plethora of options for cutting metals. While each one has its advantages and disadvantages, there is no one-size-fits-all. Industry professionals often decide on the operation to implement after a thorough investigation of the project.
So what process fits your next project?
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